de Castro Silva Junior Henrique, Antunes Uhil, Dos Santos Aline Joana Rolina Wohlmuth Alves, Moreira Eduardo Ceretta
Universidade Federal do Rio Grande do Sul - Instituto de Química, Porto Alegre, RS, Brazil.
Programa de Pós-graduação em Ciência e Engenharia de Materiais, Universidade Federal do Pampa, Campus Bagé, Bagé, RS, Brazil.
J Mol Model. 2023 Aug 29;29(9):298. doi: 10.1007/s00894-023-05685-3.
Triazene compounds (-NNN(H)-) exhibit versatility in biological, physical, and chemical applications. In their anionic form (-NNN-), they can act as coordinating sites for metals, forming metallic complexes. In this study, two new isomeric triazene compounds with meta- and para-substituents in their neutral and anionic forms were investigated. A combination of detailed experimental spectroscopic characterization and computational chemistry analyses were employed. The new compounds, 1-(2-benzamide)-3-(3-nitrophenyl) triazene (m-TZN) and 1-(2-benzamide)-3-(4-nitrophenyl) triazene (p-TZN), were compared to 1,3-diphenyltriazene (dph-TZN) to understand the effects of functionalization and targeted triazene deprotonation. The anionic forms are stable, and our investigation suggests that these new compounds are suitable tridentate ligands that can act as chelating agents for metallic cations in stable complexes, similar to those found in vitamin B12.
The absorption, vibrational, and electronic properties of the newly synthesized triazene compounds were extensively characterized using FT-IR/FT-Raman and UV-Vis spectroscopy. Their distinct molecular properties, intramolecular hydrogen bond effects, stability, and electronic transitions were investigated using the ORCA software. These analyses involved DFT and TD-DFT calculations at the ωB97X-D3/Def2-TZVP level of theory with THF CPCM implicit solvation to determine the molecular topology and electronic structure. The advanced STEOM-DLPNO-CCSD method for excited states was employed, enabling an in-depth analysis of ground and excited-state chemistry, accounting for precise electronic correlation and solvation effects. Explicit THF solvation was tested on the full TD-DFT ωB97X-D3/Def2-TZVP level and using ONIOM on the STEOM calculation. Reactivity was studied using Fukui functions, and action as chelating agents was investigated using GFN-xTB2 and DFT.
三氮烯化合物（-NNN(H)-）在生物、物理和化学应用中具有多样性。以其阴离子形式（-NNN-）存在时，它们可作为金属的配位位点，形成金属配合物。在本研究中，对两种新的异构体三氮烯化合物进行了研究，它们在中性和阴离子形式下具有间位和对位取代基。采用了详细的实验光谱表征和计算化学分析相结合的方法。将新化合物1-(2-苯甲酰胺)-3-(3-硝基苯基)三氮烯（间位三氮烯，m-TZN）和1-(2-苯甲酰胺)-3-(4-硝基苯基)三氮烯（对位三氮烯，p-TZN）与1,3-二苯基三氮烯（dph-TZN）进行比较，以了解官能团化和目标三氮烯去质子化的影响。阴离子形式是稳定的，我们的研究表明，这些新化合物是合适的三齿配体，可作为稳定配合物中金属阳离子的螯合剂，类似于维生素B12中的那些。
使用傅里叶变换红外光谱/傅里叶变换拉曼光谱（FT-IR/FT-Raman）和紫外可见光谱（UV-Vis）对新合成的三氮烯化合物的吸收、振动和电子性质进行了广泛表征。使用ORCA软件研究了它们独特的分子性质、分子内氢键效应、稳定性和电子跃迁。这些分析涉及在ωB97X-D3/Def2-TZVP理论水平下进行密度泛函理论（DFT）和含时密度泛函理论（TD-DFT）计算，并采用四氢呋喃（THF）极化连续介质模型（CPCM）隐式溶剂化来确定分子拓扑结构和电子结构。采用先进的激发态STEOM-DLPNO-CCSD方法，能够深入分析基态和激发态化学，考虑精确的电子相关和溶剂化效应。在完整的TD-DFT ωB97X-D3/Def2-TZVP水平上测试了显式THF溶剂化，并在STEOM计算中使用了多尺度模型 ONIOM。使用福井函数研究了反应活性，并使用GFN-xTB2和DFT研究了作为螯合剂的作用。
